Large parts of existing music are characterized by a sequence of stressed and unstressed beats (often called “strong” and “weak”). Beats divide the time axis of a piece of music or a musical sequence by impulses or pulses. The beat is intimately tied to the meter (metre) of the music as it designates that level of the meter (metre) that is particularly important, e.g. for the perceived tempo of the music.
A well-known instrument for determining the beat of a musical sequence is a metronome. A metronome is any device that produces a regulated audible and/or visual pulse, usually used to establish a steady beat, or tempo, measured in beats-per-minute (BPM) for the performance of musical compositions. Ideally, the pulses are equidistant.
However, humans performing music will never exactly match the beat given by a metronome. Instead, music performed by humans will always exhibit a certain amount of fluctuations compared with the steady beat of a metronome. Machine-generated music on the other hand, such as an artificial drum sequence, has no difficulty in always keeping the exact beat, as synthesizers and computers are equipped with ultra precise clocking mechanisms.
But machine-generated music, an artificial drum sequence in particular, is often recognizable just for this perfection and frequently devalued by audiences due to a perceived lack of human touch. The same holds true for music performed by humans which is recorded and then undergoes some kind of analogue or digital editing. Post-processing is a standard procedure in contemporary music production, e.g. for the purpose of enhancing human performed music having shortcomings due to a lack of performing skills or inadequate instruments, etc. Here also, even music originally performed by humans may acquire an undesired artificial touch.
Therefore, there exists a desire to generate or modify music on a machine that sounds more natural.